Fugitive dust emissions pose risks to mining companies, surrounding communities and the receiving environment, and require proper management to mitigate their effects, and environmental management company I-CAT is well poised to do so through its comprehensive solution offering.
I-CAT Environmental Management and Consulting divisional manager Leon Janse van Rensburg says fugitive dust emissions are inherently part of the mining industry, owing to the nature of mining activities, such as blasting, minerals processing activities and fugitive dust emissions emanating from haulage roads. Emissions are especially prevalent in opencast mining and associated activities, the processing of raw mine materials using crushing and screening plants, and on waste rock dumps or mine tailings through windblown activities.
While not the biggest contributor, dust emissions contribute to the overall ambient PM10 (the fraction of particulates with a diameter of 10 μm or smaller) concentration in the atmosphere. Therefore, it is still a problem that should be properly managed, Janse van Rensburg emphasises.
In terms of the environmental impact of dust emissions, dust particles can become entrained in the atmosphere, resulting in the quality of ambient air decreasing and, in some cases, cause visual impairment near the source of emission. Further, surface waterbodies can become contaminated by dust particles settling on the surface, while the biodiversity of fauna and flora in areas surrounding mining activities can also be negatively affected by dust fallout.
Janse van Rensburg highlights that surrounding communities can be affected in two ways: socioeconomically, dust contributes to the devaluation of property in a mine’s surrounding area; in terms of health, inhaling dust particles over time can lead to a range of negative health effects.
For mining companies, the impact manifests financially, such as increased maintenance for mining equipment; and operationally, such as an increase in downtime often because of visual impairment when the dust emissions become too excessive.
From a health and safety perspective, mineworkers can inhale dust emissions, resulting in a range of occupational illnesses and diseases, which could further result in increased liability to mining companies.
Janse van Rensburg indicates that I-CAT’s dust management package constitutes the actual planning and implementation of dust management measures and technologies for mines.
In terms of operational control measures, this can include something as simple as implementing speed limits on the roads, and avoiding the excessive clearing of natural vegetation on mining sites. This mitigates the prevalence of areas that are void of vegetation, as these areas contribute to excessive dust emissions as particles are mechanically entrained in the atmosphere through windblown activities.
I-CAT aims to deliver a customised solution geared specifically for the challenges of clients. The type of solution is usually dictated by the source of the dust, which can either originate from a point or non-point source. Point source dust emissions are created from a static point, such as dust emissions created from a processing crusher, while a non-point source is variable, such as dust emission originating from haulage roads.
Technologies for point source systems include misting systems, which can contribute towards restricting particles from becoming airborne by addressing the problem at the source. Essentially, a misting system encourages the binding of water molecules with dust particles, resulting in the formed particle being heavier and drawn down to the surface under gravity.
In terms of technologies for non-point systems, water can be used in conjunction with road dust palliatives for primary and secondary roads. Dust palliatives aim to bind soil particles together over a longer period while using less water, as the application frequency of using dust palliatives in an aqueous solution is far less than the application of a water-only solution, Janse van Rensburg indicates.
He emphasises that using water only is not a feasible solution for dust management and suppression, owing to the scarcity of this resource in the country. Water also tends to evaporate quickly, which, in turn, allows for small particles to become entrained in the atmosphere in a short time period.
Other measures entail enclosing conveyor areas of mining plants’ offloading points and associated extraction, and collecting the dust particles into dust-filtering and storage infrastructure.
I-CAT has been designing and supplying these solutions and technologies since 2009, with numerous clients indicating that implementing the company’s technologies has had a positive effect on mitigating the negative effects of dust emission at mines, says Janse van Rensburg.
Fugitive dust emissions are regulated under the National Dust Control Regulations (NDCR), promulgated under the National Environmental Management: Air Quality Act (NEM:AQA). The NDCR stipulates that the dust emissions from point and non-point sources are not allowed to exceed certain limits in residential and non-residential areas.
Mines are also required to comply with the National Ambient Air Quality Standards, also promulgated under NEM:AQA. This stipulates the ambient concentration limits for various compounds and particulates.
Moreover, mines need to meet compliance requirements in terms of dust management stipulated in the mines’ approved Environmental Management Programmes.
Janse van Rensburg indicates that, as part of its dust management package, I-CAT has an environmental monitoring division in the company, assisting companies with the monitoring of fugitive dust emissions in accordance with statutory requirements.
He notes that, despite I-CAT offering such a comprehensive package, the company always strives to deliver one that is economical.